1. Field of the Invention
The present invention relates in general to video and audio playback systems and in particular to methods and systems for playing audio and video from a digital source, wirelessly transferring the source data to a video display or projector and a set of digital powered speakers.
2. Background of the Related Art
Many systems are available to provide high quality playback of video and audio. Most of the systems that currently provide the highest quality of playback are built by individuals from off-the-shelf components (amplifiers, speakers, DVD/CD players).
It is widely recognized that loudspeakers provide the best sound quality when driven by multiple amplifiers. It is a typical “audiophile” practice to use separate monoblock amplifiers to drive a loudspeaker pair because it results in superior fidelity.
These amplifiers typically have separate transformers and larger power supplies, thus making it easier for each amplifier to drive an individual loudspeaker rather than a stereo pair.
Some audiophiles take this practice a step further, by using a separate monoblock amplifier for each individual transducer—meaning a pair of 3-way loudspeakers would be driven by (6) separate monoblock amplifiers. With such an arrangement, an electronic crossover may be necessary to create a uniform frequency response. This electronic crossover may eliminate the need for a passive crossover network in the loudspeaker, thus enabling the designer to experiment with steeper crossover slopes and greater frequency response correction. Designers of high-resolution loudspeakers have always been plagued by the fact that they cannot predict what kind of amplifier will be used to drive their design. In fact, of all the links in the audio chain, it is the interaction between amplifier and loudspeaker that has the greatest impact on fidelity.
Unfortunately, in the world of high-end audio, multiple amplifiers and electronic crossovers can be incredibly expensive. In addition, overall resolution can be lost if low-grade parts are used in the electronic crossover. The high cost of building such a system has severely limited its market potential. Thus, there is a need for a system that provides the crossover function and capability to tune each amplifier and speaker combination so that a manufacturer can achieve extremely high fidelity performance with relatively inexpensive parts.
One common source of trouble in existing systems is that the amplifiers must be connected to the speakers by fairly long lengths of wire, which adds additional impedance mismatches, frequency response roll-off and added distortion to the speaker system. Furthermore, the separate amplifiers are typically driven with analog audio sources, which means that it is necessary to use amplifiers with similar current and distortion characteristics in order to maintain a similar seamless sonic integration between speaker channels as well as between transducers in each speaker. Consequently, it is very difficult to mix and match different amplifier types or topologies within a loudspeaker configuration, such as a tube amplifier to drive a tweeter and a solid-state class a/b amplifier to drive a woofer. Additionally, the crossover networks are typically constructed from analog audio filters or digital filters with analog inputs and outputs. Analog level crossover networks are another primary source of signal degradation and distortion caused by the quality of components used in either a passive or electronic analog crossover, i.e. non-inductive wire-wound resistors sound better and produce less distortion than a typical sand-cast resistor, and film/foil polypropylene capacitors sound significantly better than mylar or electrolytic capacitors. Up until now, there has been no system that provides a completely digital path from the source (CD or DVD player) to the speaker transducers, while also eliminating all analog components from the signal path.
An additional difficulty arises when installing a multichannel (surround) system, in that long wires must be run to each speaker. While this can be easily accomplished when the room is being built, the majority of systems are being installed in existing homes. Even when the physical running of the wires is not a problem, degradation of sound quality always takes place whenever an analog audio signal is transmitted down a conductor, regardless of whether gold, silver, copper or even exotic materials like carbon fiber are used. The audio cable industry has spent significant amounts of money developing new and purer conductive materials, such as “6-nines” copper (99.9999% pure) and experimented with a wide array of cable construction techniques and dielectrics such as teflon in the effort to reduce impedance mismatches, ringing, distortion, and smearing or roll-off of the audio signal's frequency response before it travels down a conductor to the next audio component.
To date, most of the work done to implement wireless video has done little to address the need for high quality reproduction of the sound portion of the programming. These systems have concentrated on replacing just the video link, or simply pass a compressed and degraded version of the audio over the link to a conventional amplifier/speaker system, using a single point-to-point data link for both video and audio. Thus, there is a need for a system that separates the channels to the video and individual speakers, providing enhanced flexibility in speaker placement and eliminating much more of the conventional systems wiring.
The rise of CD, DVD and the Internet has largely supplanted analog source material as the primary playback medium. Music and video signals are now most commonly distributed to consumers in digital formats. Thus, there is a need for a system that can provide an all-digital path from the digital source to the speaker transducer so that the audio can be delivered in as close to the original form as possible.